An OLED display panel has many advantages, such as high color gamut, high contrast, light weight, thin volume, power saving or the like, which has gradually replaced an LCD display panel in the field of flat panel display and has been widely used in mobile phones nowadays. With the development of mobile technology, digital products are becoming more and more functionalization, miniaturization and portability. A smart watch as the representative of the wearable product has begun to emerge in the market. A smart wearable device, as a new product in recent years, has attracted more and more attention from the market, and it has become a product comparable to the mobile phone due to its stylish shape, functional diversity and convenience to carry. In order to improve the display performance of the smart wearable device and to achieve its miniaturization, the smart wearable device has also used the OLED display panel at present.
In order to make the display panel of the smart wearable device have a higher degree of freedom of appearance design and closer to the requirements of a user, it is inevitable that a through hole is required on the display panel of the smart wearable device. For example, as for a smart watch, the user prefers to add pointer design of a traditional mechanical pointer watch on the basis of the smart watch. Therefore, the through hole needs to be provided on the display panel in order to set the pointer.
However, at present, the packaging technology of the OLED display panel is mainly divided into two categories, one category uses materials such as a ultraviolet (UV) curing adhesive or a glass (Frit) cement to bond a substrate and cover plate together, so as to achieve a sealing effect; the other category uses a thin film encapsulation (TFE) process, so as to achieve an effect of blocking water and/or oxygen by depositing a water-resistant thin film layer on the substrate. However, regardless of which of the above two types of technology is used to package the display panel, after a through hole is provided in the center of the display panel, neither of them may prevent external water and/or oxygen permeating into the display panel via the through hole and contacting with the display element, which affects the display performance of the display element and even causes invalidation of the display element.